The oldest Mo porphyry mineralization in the Yangtze Valley Metallogenic Belt of eastern China: Constraints on its origin from geochemistry,geochronology and fluid inclusion studies at Matou     

《Ore Geology Reviews》2017

The Matou Mo(-Cu) deposit, located in the Yangtze Valley Metallogenic Belt of central-eastern China, is a typical porphyry-type Mo deposit. The orebodies at the deposit are hosted by Matou porphyritic granodiorite, which is the largest intrusive in the area. Quartz vein-type and disseminated sulfide mineralization are well developed in the porphyry and near its contact with Silurian sandstone. Crosscutting relationships indicate that porphyritic granodiorite is the oldest phase in the pluton, which is crosscut by a porphyritic diorite containing traces of chalcopyrite, and later dolerite dykes. These phases have U-Pb zircon dates of 147 ± 3, 140 ± 1 and 135 ± 1 Ma, which confirms the cross-cutting relationships observed in the field. A Re-Os molybdenite isochron age of 147 ± 4 Ma indicates that the porphyritic granodiorite is the source of the oldest Mo mineralization in the metallogenic belt and was formed during a change of the tectonic setting in the area, from an intracontinental orogeny to extensional tectonics. From 147 to 135 Ma, crust-mantle interaction played an important role in the formation of magmatic rocks at Matou. Systematic petrological and geochemistry investigations reveal that the three phases have a crust source with minor input from the mantle. Investigation of ore-forming fluid, H-O isotopes, S isotopes, and the Re content of molybdenite indicate that the ore-forming fluid and metals were derived from the lower crust. During the evolution of fluid from initial magmatic fluids (stage I) to ore-forming fluids (stage II), fluid boiling accompanied by the input of relatively cooler meteoric water led to the deposition of the Mo mineralization.  相似文献   

长江中下游成矿带矿产勘查-科研工作回顾和展望   总被引：8，自引：5，他引：3  

常印佛  周涛发  范裕 《岩石学报》2017,33(11):3333-3352

长江中下游成矿带是我国勘查-研究程度相当高的成矿带之一,地质勘查和相关研究工作可以追溯到二十世纪初。本文简要对成矿带自二十世纪初至今的勘查-科研工作成果进行了概括性回顾和综述。中华人民共和国成立后成矿带勘查研究工作总体上可以分为三个阶段:(1)第一阶段:点上起步、由点到面;(2)第二阶段:区域展开、重点突破;(3)第三阶段:立体调查、深部找矿。近年来,长江中下游成矿带的地质找矿和科学研究均取得了重要进展,主要集中在以下几方面:(1)控矿构造格架(包括大地构造,后期还尝试引入了动力学背景的探讨);(2)成岩成矿作用的时代;(3)成矿系列(系统)及其演化;(4)成矿规律;(5)深部找矿。包括本专辑(代序)20余篇文章在内的近年来的找矿新发现、新突破以及对成矿的新认识,深化了成矿带成矿理论研究,指示成矿带特别是深部"第二找矿空间"具有很好的成矿潜力,同时也揭示了成矿带值得关注和仍有待进一步研究的科学问题。  相似文献   

川西岷江河谷典型大型—巨型古滑坡特征物探解译分析     

郭桥桥  郭长宝  申维  张国华  宋昊翔  周清强 《地质力学学报》2017,23(5):788-797

在遥感解译、野外调查的基础上,采用高密度电法和电阻率测深法,并结合钻探对川西岷江河谷发育的尕米寺滑坡、俄寨村滑坡、格机寨滑坡等典型大型—巨型古滑坡的空间结构进行了勘探分析,有效确定了古滑坡的空间结构和滑带特征,并认为古滑坡的滑动面多具有高低阻相间的不稳定电性层,且滑坡前缘多位于不稳定电性层变薄收敛的地方。其中,俄寨村滑坡高低阻相间的不稳定电性层厚约0~45 m,为滑坡堆积层,古滑动面紧贴基岩面,滑动面平均埋深约30 m,弱风化基岩面埋深约5.6~61 m,强风化层厚约为3~12 m;尕米寺滑坡高低阻相间的不稳定电性层厚约2.5~43 m,为滑坡堆积层,沿剖面古滑动面平均埋深约35 m,在滑坡中部存在一圈闭的低阻异常体,推测为古河道,并与钻探结果相吻合,其埋深约56~96 m,弱风化基岩面埋深13.3~100 m,强风化及岩溶综合层厚一般约为5~20 m。基于古滑坡的地球物理勘探数据和解译结果,统计分析了川西岷江河谷地区大型—巨型古滑坡空间岩土体的地球物理物性参数,对指导该区滑坡调查分析具有重要的指导意义。  相似文献   

沙尘事件对兰州河谷大气环境PM10的影响   总被引：1，自引：0，他引：1  

贾晓鹏  陈开锋 《中国沙漠》2011,31(6):1573-1578

利用1999—2001年兰州河谷大气中空气污染物的监测数据,结合河西地区沙尘事件频次,分析了兰州河谷大气环境PM10含量的季节变化特征及其成因。结果表明,源于河西地区的沙尘暴对兰州市空气中PM10含量有重要影响,PM10浓度在冬春季较高,在夏季较低。1985—2001年16 a来河西走廊中东部沙尘事件年均约为37.6 d,兰州河谷年均沙尘事件约为24.4 d,两者表现出显著的相关性（R=0.67,P=0.003）。2001年兰州河谷1 h平均沙尘PM10浓度统计分析显示:PM10含量大于1.0 mg·m-3 的峰值,主要由河西地区沙尘暴过程引起,而PM10含量0.5~1.0 mg·m-3之间的峰值,主要由工业污染物SO2、NOx及颗粒物的排放引起。要长期有效地改善兰州市大气环境质量,不仅要科学地制定本地污染物的减排措施,还要考虑周围地区生态环境的建设。  相似文献   

基于InSAR形变数据分析台湾纵谷断层南段现今运动特征     

李海艳  邵志刚  马宏生  王芃  戴宗辉 《地震》2016,36(3):25-33

本文利用2007—2010年花东纵谷南段区域的InSAR形变数据作为约束, 采用分段断层模型和层状介质模型, 反演中国台湾东部纵谷断层南段滑动速率空间分布, 并据此分析断层运动特征。 研究结果表明, 纵谷断层南段整体以逆冲运动为主, 兼具左旋走滑运动。 纵谷断层南段的滑动速率具有空间非均匀性, 在空间上可以细分为深浅两个极值区, 浅部(0~15 km)最大滑动速率为10 cm/a, 位于深度2.5 km左右; 深部(15~30 km)最大滑动速率为21 cm/a, 位于深度25 km左右。 反演结果与用重复地震估算的深部滑动速率基本吻合。  相似文献   

Isolated Archosaur teeth from the green sandstone capping the Coralline Limestone (Bagh Group) of the Narmada valley: Evidence for the presence of pre‐Late to Late Maastrichtian abelisaurids in India          下载免费PDF全文

Guntupalli V.R. Prasad  Vishal Verma  Pooja Grover  Rajkumari Priyadarshini  Ashok Sahni  Ranjit S. Lourembam 《Island Arc》2016,25(6):410-420

Recent field prospecting in the Cretaceous sequences of the lower Narmada valley has led to the discovery of three isolated archosaur teeth from the upper part of marine Cretaceous rocks of the Bagh Group. The specimens were recovered by surface prospecting from an oyster‐bearing green sandstone bed occurring at the top of the Coralline Limestone (Coniacian) from a site near Phutibawri village, Dhar District, Madhya Pradesh, India. Of the three teeth recovered from this horizon, two are identified with abelisaurid dinosaurs and the third one with an indeterminate crocodile. The abelisaurid teeth conform to the premaxillary and maxillary tooth morphology of Majungasaurus and Indosuchus. Earlier reports of abelisaurid dinosaurs from India are from the Upper Cretaceous (Maastrichtian) Lameta Group of Jabalpur, Pisdura (Central India) and Balasinor (Western India) and Upper Cretaceous (Late Maastrichtian) Kallamedu Formation (South India). As no associated age diagnostic fossils are found, the specimens described here are considered to represent pre‐Late to Late Maastrichtian age based on the known ages of the underlying and overlying formations. The new finds, therefore, document stratigraphically the oldest occurrence of abelisaurid dinosaurs known from the Indian subcontinent.  相似文献   

四川宁南县银厂沟-骑骡沟铅锌矿床成因浅析   总被引：3，自引：0，他引：3  

杨红英  钟康惠  刘清双  周慧文 《四川地质学报》2009,29(1):24-28,36

四川宁南县银厂沟-骑骡沟铅锌矿床产于震旦系上统灯影组白云岩中,主要受断裂控制。矿体多为透镜体状、网脉状和细脉状。与成矿有密切关系的硅质条带为富硅热液后期充填产物,显示后期热液充填成矿特点。分析研究认为该矿床在成矿的大地构造背景和其它特点方面,均与美国中部密西西比河谷型（MVT型）铅锌矿有相似性。  相似文献   

综合工程物探在九寨沟核心景区水循环系统研究中应用评价     

武斌  汪智  张淳  刘鹏鹏  易攀 《四川地质学报》2009,29(2):213-216

综合物探技术是一种高新技术,在岩土工程中有广泛的应用前景。文章介绍了瑞雷波勘探和直流电法在九寨沟核心景区水循环系统中的应用,对方法原理进行了简单阐述,并探讨了对综合工程物探技术在九寨沟景区第四系化学沉积钙华层和冰碛地层的划分的分析评价。  相似文献   

湖北省钟祥市汉江河谷平原区浅层孔隙水的脆弱性评价   总被引：1，自引：1，他引：0  

袁建飞  郭清海 《地质科技情报》2009,28(4)

以MAPGIS为工作平台,以地下水类型、盖层岩性、地下水埋深为评价指标,利用国际上广泛应用的GOD模型开展了湖北省钟祥市第四系浅层孔隙水的脆弱性评价.研究结果表明:区内浅层孔隙水的脆弱性评分值在0～0.7间,其中极低脆弱性区(评分值=0～0.1)、低脆弱性区(评分值= 0.1～0.3)、中等脆弱性区(评分值=0.3～0.5)、高脆弱性区(评分值=0.5～0.7)和极高脆弱性区(评分值=0.7~10.0)的面积分别占评价区总面积的0.3 %,0.0 %,64.1 %,35.6 %,0. 0 %.换言之,钟祥市汉江河谷平原区浅层孔隙水总体上具有中等脆弱性和高脆弱性,且脆弱性最高的地段几乎全部分布在汉江沿岸.为解决钟祥市工农业发展带来的高污染风险性与地下水具有较高脆弱性这一对明显的矛盾,应加强汉江河谷平原区的地下水资源的管理工作.  相似文献   

Constraints to effective adoption of innovative livestock production technologies in the Rift Valley (Kenya)     

《Journal of Arid Environments》2013

We surveyed small-scale farmers in the Kenyan Rift Valley province (Narok and Nakuru districts) to describe constraints to, and changes in, livestock production and to assess the extent to which farmers have adopted new technologies promoted by extension services. In the arid areas of southern Narok, farmers' main constraints were drought and disease. Farmers in Nakuru district, situated in the fertile highlands of the Rift Valley, were also affected by disease but also lacked markets and capital. Although 83% of the farmers had regular contact with extension services that provided advice on new technologies and livestock production innovations, only about half of the respondents implemented the proposed changes. Many of those who did change (38%) improved pasture/nutrition/manure management and relatively few (16%) improved their animal breeding practices. Results of a multinomial logit model revealed that, apart from the significant differences between the two districts, the nature of the advice and the expected outcomes had the strongest influence on the probability of successfully implementing changes to livestock production. The results further suggest that adoption of new technologies is limited by lack of knowledge, inadequate support and a failure to target local needs and conditions and empower livestock keepers.  相似文献